My VPS is Out of RAM how much to I need more?

view full story

http://serverfault.com – I have VPS server with 1.25GB ram and 0.51GB cache trying to up an e-commerce website with 200k items, db now is about 2gb anything is now works terrible slow now because of lack memory mysql queries takes about 30 seconds to complete on the peak memory usage. so is there any methods how to calculate how much to i need to extend RAM of my VPS? [root@ssrv/]# free -m total used free shared buffers cached Mem: 1247 1209 38 0 1 48 -/+ buffers/cache: 1159 88 Swap: 511 174 337 (HowTos)